MAX4501 Maxim, MAX4501 Datasheet - Page 6

• Manufacturer Part Number: MAX4501
• Description: The MAX4501/MAX4502 are single-pole/single-throw (SPST), low-voltage, single-supply, CMOS analog switches
• Manufacturer: Maxim

Low-Voltage, SPST, CMOS Analog Switches
Note: NO, NC, and COM pins are identical and interchangeable. Any may be considered as an input or an output; signals pass
The MAX4501/MAX4502 are constructed like most
CMOS analog switches, except they have only two sup-
ply pins: V+ and GND. V+ and GND drive the internal
CMOS switches and set the analog voltage limits of the
switch. Reverse ESD-protection diodes are internally
connected between each analog signal pin and both
V+ and GND. One of these diodes conducts if any ana-
log signal exceeds V+ or GND. During normal opera-
tion, these and other reverse-biased ESD diodes leak,
forming the only current drawn from V+ or GND.
Virtually all the analog leakage current comes from the
ESD diodes. Although the ESD diodes on a given sig-
nal pin are identical and therefore fairly well balanced,
they are reverse biased differently. Each is biased by
either V+ or GND and the analog signal. This means
their leakages will vary as the signal varies. The differ-
ence in the two diode leakages to the V+ and GND
pins constitutes the analog signal-path leakage current.
All analog leakage current flows between each pin and
one of the supply terminals, not to the other switch ter-
minal. This is why both sides of a given switch can
show leakage currents of the same or opposite polarity.
There is no connection between the analog-signal
paths and V+ or GND.
V+ and GND also power the internal logic and logic-
level translators, and set the input logic limits. The
logic-level translators convert the logic levels to
switched V+ and GND signals to drive the analog sig-
6
______________________________________________________________Pin Description
SO/DIP
2, 3, 5
_______________________________________________________________________________________
—
1
4
6
7
8
equally well in both directions.
MAX4501
SC70-5/SOT23-5
Applications Information
Power-Supply Considerations
—
—
1
5
4
3
2
PIN
SO/DIP
2, 3, 5
—
1
4
6
7
8
MAX4502
SC70-5/SOT23-5
—
—
1
5
4
3
2
nal gates. This drive signal is the only connection
between the logic supplies (and signals) and the ana-
log supplies. COM, NO, and NC pins have ESD-protec-
tion diodes to V+ and GND.
The logic-level thresholds are CMOS/TTL compatible
when V+ is +5V. As V+ rises, the threshold increases
slightly. When V+ reaches +12V, the logic-level thresh-
old is about 3V—above the TTL guaranteed high-level
minimum of 2.8V, but still compatible with CMOS out-
puts.
Do not connect the MAX4501/MAX4502’s V+ pin to
+3V and then connect the logic-level pins to TTL
logic-level signals. TTL levels can exceed +3V and
violate the absolute maximum ratings, damaging
the part and/or external circuits.
In 50Ω systems, signal response is reasonably flat up
to 250MHz (see Typical Operating Characteristics).
Above 20MHz, the on-response has several minor
peaks that are highly layout dependent. The problem is
not in turning the switch on; it’s in turning it off. The off-
state switch acts like a capacitor and passes higher
frequencies with less attenuation. At 10MHz, off-isola-
tion is about -60dB in 50Ω systems, decreasing
approximately 20dB per decade as frequency increas-
es. Higher circuit impedances also cause off-isolation
to decrease. Adjacent channel attenuation is about 3dB
above that of a bare IC socket, and is due entirely to
capacitive coupling.
NAME
COM
GND
N.C.
NO
NC
V+
IN
Analog Switch Common Terminal
No Connection. Not internally connected.
Positive Supply-Voltage Input (analog and digital)
Digital Control Input
Ground
Analog Switch (normally open)
Analog Switch (normally closed)
High-Frequency Performance
FUNCTION